The present invention relates to transformers for supplying power to lighting fixtures or other electrical equipment, such as fountains positioned in bodies of water, and which utilize photocells to control the power supplied by the transformer in response to changes in ambient light levels.
Transformers for providing electrical power to outdoor utilities or fixtures, including sub-grade or underwater lighting, are known in the prior art and include transformers for supplying low voltage power thereto. Photocells have been used to control electrical power supplied to fixtures associated with such transformers; however, they are typically separated by a length of conduit from the body of the transformer. While operable, such systems often require some on-site assembly and existing systems are not known to have been rated for submergence. The transformers used in such systems are typically maintained on shore or on a float associated with the lighting or other electrical equipment and are not specifically intended to be submerged. However, the current National Electric Code (2005) requires that electrical equipment and transformers that are maintained within a certain vertical distance relative to a normal level for specified types of bodies of water must be rated for submergence.
As used herein, the term “photocell” refers to a pre-assembled, photoelectric component existing in the prior art. A photocell typically includes a photodetector such as a photoresistor, photodiode, phototransistor or photovoltaic cell. Photocells, and associated circuitry and mounting hardware, may be used to regulate 120V or 240V electrical power such that power is allowed to flow through the regulated circuit when no or minimal light strikes the photocell, and power is not allowed to flow through the regulated circuit when light, of an intensity typically considered sufficient to constitute daylight, strikes the photocell. Most commonly, the photosensitivity of a photocell is provided by a cadmium sulfide photoresistor.
The term “transformer” is intended to have its ordinary meaning and generally refers to an electrical device that uses magnetic coupling to enable a primary circuit to induce a current in a secondary circuit. Typically, high voltage electrical power is provided to the transformer, in which lower voltage electrical power is thereby induced.